Many types of concrete deck structures include expansion/contraction joints between abutting front and rear surfaces of adjacent concrete slabs to provide a continuous deck structure. However, stresses imparted on the deck structure often bring about erosion of the concrete in the immediate vicinity of the joint due to cracking, edge failure and faulting. In order to avoid the need to replace an entire length of concrete slab having damaged edges, many concrete deck structures include a foot wide replaceable composite concrete header at the front and rear ends of each concrete slab.
One method presently used for the construction of concrete deck structures involves pouring and forming the concrete headers in situ on top of the existing deck and in front and rear ends of each concrete slab. Typically, the upper edge of each header adjacent the expansion and compression joint is fitted with a steel angle to protect the concrete from eroding. The steel angle spans the entire width of the header and is mounted to the concrete slab by support angles. During curing, the concrete header bonds to the complementary surfaces of the concrete slab.
A procedure currently used to replace damaged concrete headers consists of removing the damaged header, cleaning and sandblasting the recessed surface of the concrete slab, mounting a steel angle to the concrete slab, pouring concrete into the recess formed in the concrete slab and thus forming the new header in situ.
However, there are significant drawbacks to these currently practiced procedures. First, concrete headers require up to seven days to cure. In order to use the concrete deck structure during this seven-day curing period, roadway steel plates must be placed over each concrete header to prevent deformation caused by automobiles, heavy construction equipment or other vehicles traveling on the deck structure. However, these roadway steel plates have been known to create hazardous conditions that can result in serious accidents when automobiles travel over the plates at excessive speeds.
Secondly, the replacement of damaged concrete joints is typically limited to off peak traffic periods, usually between the hours of 11 p.m. and 6 a.m. Therefore, the construction contractor must incur the added cost and inconvenience of obtaining an off hour supply of concrete to form the concrete headers in situ. Inclement weather conditions can also interfere.
Thus there exists a compelling need for a safe, efficient and cost-effective method for forming and installing concrete headers in concrete deck structures.